Formula and Amounts of a Substance

• How do you work out the mass % of an element?

  mass of element in 1 mole

  ------------------------ x100

  molar mass of the compound
• Emperical Formula

  The simplest whole number ratio of atoms in each element in the compound.
• Molecular Formula

  The actual number of atoms of each element in a molecule.
• How do you calculate the moles of gas?

  volume(dm3) volume(cm3)

  -------------- OR ---------------

  24 24,000
• How do you calculate % yield?

  actual yield

  ------------ x 100

  theoretical yield
• Atom Economy

  mass of usefull/desired product

  ------------------------------- x 100

  mass of all the products
• Why is a high atom economy important?

  For sustainable development (better for the envionment), and for economic reasons.
• Molar Gas Volume

  The volume of 1 mole of gas under specific conditions of temperature and pressure eg, 24 dm3 at 20 (293 K) and 1 atmosphere pressure.